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Before you remove something you don’t understand, find out why it’s there. A rule, process, or boundary that looks pointless may be quietly preventing a problem you’ve never seen, because someone already solved it.
The Dr. Wallace’s Favorite Mental Models is designed to turn useful ways of thinking into reusable tools. Each model gives you a fast visual overview, deeper interactive learning, practical application exercises and an AI-ready Markdown skill you can save for future use.
Instead of merely reading about mental models, you can gradually build your own AI skills library: a collection of portable reasoning skills that can help ChatGPT, Claude, Grok and other AI assistants apply the mental models you value.
When you find a rule, restriction, or step that seems useless, resist removing it immediately. Find out why it was built first. If no one can explain it, investigate before you act.
Important: the goal isn’t to keep every fence forever. It’s to learn its purpose before deciding whether to keep, remove, or replace it.
The model is most useful when a rule, process, or structure looks obsolete or pointless, and someone is about to remove it without checking its history first.
The method slows down removal just long enough to find out what a rule was actually protecting against.
Spot a rule, step, boundary, or structure that looks unnecessary, outdated, or overly cautious.
Find out directly whether anyone currently knows the original reason it was created.
If no one knows, check documentation, history, prior incidents, or the people who were there.
Keep, remove, modify, or replace it, once the purpose is understood or a reversible test is safe.
Open a use case to see what the model changes.
Before deleting a legacy feature flag or a strange conditional, check version history and incident logs. It may exist because of an edge case that will reappear the moment it’s gone.
Ask who added the step and what it followed. A manual sign-off added after a costly mistake is protecting against a specific, known failure, not bureaucracy for its own sake.
Ask the person who made the rule why it exists before dropping it. Some family rules encode a real lesson learned the hard way; others really have outlived their purpose.
Research the original problem the regulation addressed. If that problem could recur without it, repeal should come with a plan for the risk it was managing, not just removal.
Check whether a small but important segment of users depends on it before removing it. Usage data can miss infrequent but critical use.
Learn why the structure was set up before flattening it. It may exist to resolve a conflict, ensure a check, or serve a coordination need that isn’t obvious from the org chart.
This is an illustrative example designed to teach the method.
Expand for the distinction between Chesterton’s original argument and the way it’s commonly paraphrased today.
G. K. Chesterton was an English writer and essayist. In his 1929 essay collection "The Thing," he described a reformer who encounters a fence across a road and wants to tear it down because he sees no reason for it. Chesterton argued the reformer should first go away and find out why it was put there, and only then decide whether to remove it.
No. The short, quotable phrasing widely used today is a paraphrase of Chesterton’s argument, not a verbatim line from the essay. The underlying point, that not understanding a rule is not the same as the rule having no purpose, is faithful to his original argument.
No, and the difference matters. Status quo bias describes an irrational preference for keeping things as they are. Chesterton’s Fence is the opposite caution: it warns against removing things too quickly, but it does not argue for keeping everything. Once the reason is understood, removal is a legitimate and often correct choice.
The model does not argue against removing or changing anything. It argues for understanding first. Once understood, removal is fine.
"Nobody remembers why" is a sign to investigate further, not evidence that no reason exists.
Investigation should be proportional to risk. A reversible, low-cost change doesn’t need an exhaustive history search.
Some fences were built for a reason. Others are just habit repeated without justification. Both look the same from the outside until investigated.
If you discover the reason, write it down. Otherwise the next person repeats your entire investigation.
An active safety or legal risk needs action now. This model is for deliberate removal decisions, not emergencies.
there is a live safety, legal, or financial emergency where delay itself causes harm.
the origin is already well documented and clearly no longer applies, or the test is small and fully reversible.
the "fence" restricts a person’s own autonomy and the burden of proof should fall on whoever imposed the restriction, not on the person questioning it.
This browser tool structures your thinking. It does not send your information anywhere or perform AI analysis.
Save as Skill converts the model into portable Markdown instructions that teach an AI when and how to apply Chesterton’s Fence, what questions to ask, what evidence to seek, what mistakes to avoid and how to structure its analysis.
Save the skills you find useful and organize them into your own reusable library. The Markdown is intentionally model-neutral, so it can be used wherever an AI system accepts uploaded files, project knowledge, custom instructions or reusable text context. Platform capabilities differ, so this is a portable skill file rather than a claim of one-click installation.
No. Understanding the reason is the whole point of being able to make a real decision. Once you know why a fence was built, you might still remove it, because the original problem no longer exists, because you have a better solution, or because the cost now outweighs the benefit.
Then test it, in a small and reversible way where possible. The model’s goal is informed decisions, not maximum delay. A reversible test that surfaces the original problem quickly can be a legitimate form of investigation.
Resistance to change opposes the change itself. Chesterton’s Fence opposes uninformed change. It has nothing to say against a change made by someone who understands what they’re removing and why it’s safe to do so.